(1). Field of the Invention
This invention pertains to computer design. Applicant designates a computer designer as one having ordinary skill in the art. Therefore, this application is written so that a computer designer would be able to make and use the invention. In this regard, an operating manual is submitted herewith as an appendix to this application explaining operation of the apparatus.
This invention is to be used with telephone communications, cables; and particularly to aid in identification and analysis of status and condition of the pairs of wire in a telephone cable.
(2) Description of the Prior Art
The normal telephone system includes a central office where the telephone switching occurs, and from the central office extend many cables, each having many pairs of wire. These pairs of wire will extend to another central office or into the field to individual telephones. Before this invention, it had been common practice in the telephone systems to inspect the different pairs of wire in a telephone cable in the field.
Between the central office and the phone there are numerous junction boxes or the like. Before this invention, it was known that a certain analysis could be made at these junction boxes or any point the wire pairs of the cable were accessible.
The two wires of a pair are designated in the phone system as the ring and tip. One wire being the ring and one wire being the tip of each pair. It was known that various tests could be made; e.g., the voltage determined between the ring and tip, the ring and ground, and tip and ground. Also, in the absence of voltage, the resistance from ring to tip, ring to ground, and tip to ground could be determined. It was known that if these measurements were of certain value, it could be determined whether the pair was a "plain old telephone service" (herein called POTS) and also from this whether the pair was an idle or a busy POTS.
Typically in the standard telephone system used in the United States, the POTS will have a voltage from ring to ground of about -50 volts, + or -5 volts, and the tip will have a low resistance from tip to ground. I.e., it will have a typical tip to ground resistance of 1,000 ohms, when idle. When busy, the tip to ground will have a voltage of approximately -15 volts, + or -9 volts.
Furthermore, equipment existed before this invention to measure the capacitance. The capacitance between the ring and tip could be measured. The standard wire in common use would have a certain capacitance of per thousand feet. Therefore, by measuring the capacitance between ring and tip, a measurement could be obtained of the total length of wire. If the capacitance from ring to ground did not equal the capacitance from tip to ground, this difference indicated that the pair was unbalanced.
Furthermore, it was known, because of certain external conditions, the voltage of the wires would vary on an instantaneous basis. Therefore, for accuracy, no reading should be instantaneous, but the average of multiple readings. Of course with structural devices, such as a volt meter having a needle indicating the volts, the inertia of the physical parts act as to average the reading inasmuch as the change in voltage would be so rapid that the needle could not physically move, but because of inertia, would average the instantaneous values.